Generally, an advanced driver assistance apparatus serves to determine a driver's state and surrounding environment based on a camera, a radar, an ultrasonic sensor, and the like so as to assist a driver. An example of the advanced driver assistance apparatus may include a cruise control apparatus, a parking assistance apparatus, a lane change apparatus, a driver state monitoring apparatus, a collision alert apparatus, and the like.
Among those, the driver state monitoring apparatus may sense a pupil motion of a driver, a frequency of eye blink, a gaze direction, and the like using a camera to monitor drowsy driving and a forward gaze state of a driver. As such, when a driver's eyes are detected by the camera, to reduce an effect of sunlight incident on a vehicle and externally incident light such as a street light, a camera flash is operated. However, the camera flash may be reflected from glasses (or sunglasses) and thus may obscure the eyes (in particular, pupil and corneal reflection point), and as a result, it may be difficult to track a gaze and monitor a driver state.
Further, when the externally incident light is directly reflected from glasses, the externally incident light may obscure the eyes and thus it may be difficult to detect the eyes.